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# We're on the Same Wavelength Trivia Quiz

### From the longest radio waves to cosmic radiation, the measurable electromagnetic spectrum spans a range of 10 to the 20th power. Let's take a trip through the wavelengths from longest to shortest!

A multiple-choice quiz by WesleyCrusher. Estimated time: 6 mins.

Author
Time
6 mins
Type
Multiple Choice
Quiz #
349,201
Updated
Dec 03 21
# Qns
10
Difficulty
Tough
Avg Score
6 / 10
Plays
559
Awards
Top 35% Quiz
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Question 1 of 10
1. The lowest named band of radio waves is ELF, standing for "extremely low frequency". Where would you most commonly encounter such an electromagnetic wave? Hint

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Question 2 of 10
2. Going up a step, the next band is called VF, encompassing frequencies from 300 to 3,000 Hertz - also usually transmitted through cables. Which common application (related to the "V") uses this band? Hint

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Question 3 of 10
3. Ranging from 3 to 30 kilohertz, the VLF (Very Low Frequency) band is the lowest radio band typically used for wireless transmission. It is also the only band that can be used to meaningfully communicate with a specific type of vessel - which one? Hint

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Question 4 of 10
4. The next four bands - LF, MF, HF and VHF - are all used for analogue radio (audio) broadcasting. They stand, in turn, for long, medium, high and very high frequency. Which of them is most suitable for transmitting a radio program to be heard all around the world from a single transmitter? Hint

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Question 5 of 10
5. Staying within the audio broadcasting bands for a moment, there are two possible methods of modulating the sound signal to the carrier frequency: Amplitude Modulation (AM) and Frequency Modulation (FM). Which of the four radio bands are used for FM radio? Hint

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Question 6 of 10
6. Before we move outside radio range, here's one last question about its highest bands - SHF (Super-High Frequency) and EHF (Extremely High Frequency). Which of these is NOT a typical application using the SHF and EHF bands? Hint

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Question 7 of 10
7. Once wavelengths go below 1 millimeter (and frequencies surpass 300 Gigahertz), we leave the spectrum of radio waves and enter the infrared spectrum which, in turn, ranges all the way to approximately 0.75 micrometers. Which of the following harmful effects would a strong infrared beam immediately have on a section of unprotected human skin? Hint

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Question 8 of 10
8. There are enough quizzes about visible light already, so I'll skip right across it and go to the ultraviolet range. Which of these technological applications does NOT commonly use ultraviolet radiation? Hint

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Question 9 of 10
9. Two more regions of the spectrum to explore: Ranging from 10 nanometers to approximately 10 picometers, the X-ray spectrum is known mostly for its medical imaging applications. Which of these statements about a typical medical X-ray device is true? Hint

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Question 10 of 10
10. Finally, we have reached the gamma ray band which actually, in terms of wavelength, somewhat overlaps the X-ray band. What however does distinguish the two? Hint

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Quiz Answer Key and Fun Facts
1. The lowest named band of radio waves is ELF, standing for "extremely low frequency". Where would you most commonly encounter such an electromagnetic wave?

The ELF band encompasses the frequency from 3 to 300 Hertz (cycles per second). It is not a band used for significant radio transmission due to the need for extremely large transmitter and receiver antennas. However, normal household power - AC voltage cycled at 50 or 60 Hertz - falls into this band. ELF waves also occur in nature as a result of lightning strikes.

Some sources subdivide the ELF band into two sub-bands, using ELF only for frequencies to 30 Hz and naming the 30 to 300 Hz band as SLF (Super Low Frequency).
2. Going up a step, the next band is called VF, encompassing frequencies from 300 to 3,000 Hertz - also usually transmitted through cables. Which common application (related to the "V") uses this band?

The "V" in VF stands for "Voice" and the VF band is the spectrum used in traditional analog telephones which indeed do not transmit frequencies outside the 300 to 3,000 Hertz range well. Another name for this band is ULF (Ultra-Low Frequency); however, since practically no wireless applications for this frequency range exist, the VF designation is the most common.
3. Ranging from 3 to 30 kilohertz, the VLF (Very Low Frequency) band is the lowest radio band typically used for wireless transmission. It is also the only band that can be used to meaningfully communicate with a specific type of vessel - which one?

Waves shorter than the VLF range cannot penetrate water while waves longer than it are not only extremely hard to produce in significant strength but also cannot carry any significant data rate. Even VLF radio has too narrow a bandwidth to support a clearly modulated voice signal, so transmission is limited to low-bit-rate digital data such as navigational information. VLF signals can be received up to approximately 40 meters below the surface - deep enough for most submarine operations.
4. The next four bands - LF, MF, HF and VHF - are all used for analogue radio (audio) broadcasting. They stand, in turn, for long, medium, high and very high frequency. Which of them is most suitable for transmitting a radio program to be heard all around the world from a single transmitter?

When transmitted through the atmosphere, both MF and LF waves create so-called ground waves - they do not propagate in a straight line but actually follow the curvature of the earth due to the moisture present in the ground and seas actually bending the wave. HF and VHF waves both are unaffected by this phenomenon, but HF waves have the additional property of being relected quite well by the upper atmosphere (the ionosphere), thus "bouncing" around the globe. VHF and shorter waves do not show this reflection except under specific, uncommon atmospheric conditions and thus communication is usually limited to line of sight.
5. Staying within the audio broadcasting bands for a moment, there are two possible methods of modulating the sound signal to the carrier frequency: Amplitude Modulation (AM) and Frequency Modulation (FM). Which of the four radio bands are used for FM radio?

The VHF band ranges from 30 to 300 Megahertz, but FM radio only uses the small region from 87.5 to 108 Megahertz (depending on jurisdiction, these numbers may be slightly different). Due to the fact that VHF transmitters and receivers are among the easiest to build, any bandwidth in this region is very valuable and many services, including all communication with airplanes, many emergency systems, and a small number of television channels use this band, but most television broadcasting occurs in the next higher UHF (Ultra-High Frequency) band.
6. Before we move outside radio range, here's one last question about its highest bands - SHF (Super-High Frequency) and EHF (Extremely High Frequency). Which of these is NOT a typical application using the SHF and EHF bands?

The microwave oven actually uses a frequency (around 2.4 Gigahertz) that is still in the UHF band while all other applications use the frequency band of 3 to 300 Gigahertz. At these high frequencies, it usually becomes much easier to talk about them in terms of wavelengths, thus SHF and EHF represent waves of 10 centimeters down to 1 millimeter. Radar and wireless networks currently mostly operate in the 1 to 10 centimeter band, but plans exist for both to expand into the largely unused millimeter band.

The controversial touchless security scanners introduced at airports around 2010 also operate in the millimeter band.
7. Once wavelengths go below 1 millimeter (and frequencies surpass 300 Gigahertz), we leave the spectrum of radio waves and enter the infrared spectrum which, in turn, ranges all the way to approximately 0.75 micrometers. Which of the following harmful effects would a strong infrared beam immediately have on a section of unprotected human skin?

Infrared radiation (often inaccurately called thermal radiation or heat rays) are invisible to the human eye, but are easily felt due to their strong tendency to heat up any material they are absorbed by. Unlike microwaves, which specifically heat only water, infrared radiation is readily absorbed by almost any material and converted into heat. Strong infrared radiation can heat materials to several hundred and even thousand degrees centigrade within a fraction of a second and thus cause severe burns or ignite fires. Most immediate casualties from the nuclear attacks on Japan in World War II were actually due to this infrared radiation - bodies were burned or even vaporized by it.

It is by the way inaccurate to consider infrared waves themselves as heat - they have no temperature by themselves. Heat is generated when these waves are absorbed by materials; thus an infrared radiator can heat a solid several meters away without affecting the air in between.
8. There are enough quizzes about visible light already, so I'll skip right across it and go to the ultraviolet range. Which of these technological applications does NOT commonly use ultraviolet radiation?

Short-wavelength UV light is used both to thoroughly disinfect water and other transparent liquids and gases and to create the lithography patterns used in microchip design. In forensic analysis, longer-wavelength UV is being used to excite fluorescence in bodily fluids left behind at a crime scene - UV detectors can easily make visible blood and saliva traces that would be impossible to detect via normal inspection. Night vision devices usually use the infrared spectrum.
9. Two more regions of the spectrum to explore: Ranging from 10 nanometers to approximately 10 picometers, the X-ray spectrum is known mostly for its medical imaging applications. Which of these statements about a typical medical X-ray device is true?

Answer: It has less than 5% energy efficiency

Even with today's technology, it is impossible to directly create X-rays using a chip like in a laser or LED. Instead, a vacuum tube is used in which electrons are accelerated to extremely high speed and then colliding with other materials (typically metal atoms), dissipating their impact energy as a high-powered photon. Even in this reaction, however, less than one percent of the energy actually results in usable "hard" X-ray radiation (the longer wavelengths of so-called "soft" X-rays are filtered out as they are easily absorbed by tissues, thus only adding to the harmful radiation dose while contributing nothing to the image).
10. Finally, we have reached the gamma ray band which actually, in terms of wavelength, somewhat overlaps the X-ray band. What however does distinguish the two?

Answer: Gamma ray emission involves a nuclear reaction

The once hard wavelength boundary of 10 picometers distinguishing between X-rays and gamma rays has been replaced with a definition according to source: X-rays are the result of a process that does not involve a nuclear reaction while gamma rays are caused by a nuclear reaction, be it a decaying nucleus, a byproduct of a nuclear fusion or fission or any other such source. Powerful X-ray generators can today produce radiation in the traditional gamma band while some nuclear decays emit gamma rays that approach or even break the lower bound of the X-ray band. Gamma rays from normal radioactive decay can range down to 0.1 picometers of wavelength, while the shortest wavelengths measured from astronomical sources are actually still much shorter - all the way down to 1 attometer (one millionth of a picometer).
Source: Author WesleyCrusher

This quiz was reviewed by FunTrivia editor CellarDoor before going online.
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